The purpose of the Virus-Primary Cell Core is to provide comprehensive support for virus and primary cell-based studies in order to enhance the productivity and efficiency of established HIV investigators within the Penn/Wistar/CHOP community, facilitate the entrance of new investigators into the field of AIDS research, and promote scientific collaborations among these investigators. The core will provide: (1) a carefully supervised facility for Biosafety Level 3 training and for the performance of containment experiments by investigators without access to individual containment facilities or who require a level of containment greater than currently available; (2) a central repository of prototype HIV-1 strains, mutant virus strains, and well-characterized primary virus isolates representing different aspects of pathogenesis; (3) a service for primary HIV-1 isolation, titration and characterization, and; (4) a specialized primary cell program that will facilitate utilization of specialized primary cell types relevant to HIV studies (by providing cells for pilot experiments, training of investigations in the isolation of specialized cell types, and facilitating collaborative interaction) and by providing blood mononuclear cells with defined genotypes important for HIV studies (CCR5, CCR2b, SDF-1). It is our expectation that this core will enhance collaborations and productivity among existing HIV investigators and facilitate the entrance of non-HIV investigators into the field while providing a mechanisms to enhance laboratory biosafety.